The present invention relates to a joining assembly for mounting a fastening element of thermoplastic material to a structural member of thermoplastic material.
Quite often it is necessary to have structural members of plastics such as plastic housings provided with fixing means enabling to mount other members to said structural members. To this end it has become known for example to press threaded inserts of a harder plastic material into respective openings of the structural members, for example by a hot melt operation, ultrasonic welding or the like. This method, however, cannot be used with thin-walled structural members such as housings of mobile telephones (cellular phones). One possibility would be to provide the structural member with an integral threaded projection by injection moulding. However this is possible only with structural members of very simple geometrical shape.
It is a general object of the invention to provide an improved joining assembly for mounting a fastening element of thermoplastic material to an external surface of a structural member of thermoplastic material, which avoids the disadvantages of prior joining assemblies while affording additional structural and operating advantages.
It is a further object of the invention to provide a joining assembly which allows to mount a fastening element to a structural member after the structural member has been manufactured even though no opening in the external surfaces of the structural member is required to mount the fastening element to the structural member.
The joining assembly of the present invention comprises a fastening element having a main body provided with functional means and a joining projection integral with said main body. The structural member is provided with a joining extension integral with the external surface of the structural member and having a receiving opening for receiving the joining projection of the fastening element. The joining projection and the joining extension have matingly shaped joining surfaces which are integrally joined to each other by melting.
This allows to mount the fastening element to the external surface of the structural member so as to be integral therewith without the need to have the walls of the structural member provided with a bore, recess or the like. The fastening element may be a simple element made by injection moulding.
For integrally joining the fastening element and the structural member a conventional melting method such as ultrasonic welding or linear or rotation friction welding may be used. The fastening element and the structural member may be made of the same thermoplastic material or of different thermoplastic materials which are compatible with each other. To this end partially crystalline or amorphous thermoplastic materials, along with conventional fillers if desired, may be used.